Added hasMember and getMember function.

With these functions it is possible to check a complicated struct if a
specific member exists.

lib/+artoa/+data/getMember.m

+function [memberValue] = getMember(pStructure, pMember, pDefaultValue)
+%GETMEMBER Returns the given member in the structure if existent, the given default value otherwise.
+%   Checks for the existence of the member by using artoa.data.hasMember.
+%   If the value exists, it will be returned. Otherwise it will return the
+%   default value.
+%
+%   Parameters:
+%       pStructure (struct)   The structure where the member is stored in.
+%       pMember (cell)        A 1D cell of chars, each entry representing the
+%                             level of the structure.
+%       pDefaultValue (mixed) The default value that is returned if the
+%                             member does not exist.
+
+%% Initialization
+if ~exist(pDefaultValue, 'var')
+    pDefaultValue = '';
+end
+
+memberValue = pDefaultValue;
+
+%% Return member if it exists
+if ~artoa.data.hasMember(pStructure, pMember)
+    return;
+end
+
+memberValue = pStructure;
+for i = 1:length(pMember)
+    memberValue = memberValue.(pMember{i});
+end
+
+end
+

lib/+artoa/+data/hasMember.m

+function [boolean] = hasMember(pStructure, varargin)
+%HASVARIABLE Checks the given structure if the member is available.
+%   Checks if the fields are available in the given structure.
+%   Example:
+%       hasMember(S, 'hello', 'world')
+%       checks if S.hello.world member is available.
+%   Parameters:
+%       pStructure (struct) The structure where the member will be
+%                           searched for.
+%       varargin (char)     Every additional char array represents the
+%                           level of the structure.
+%
+%   Returns (bool) False if the member is not available.
+
+%% Initialization
+boolean = false;
+
+%% Parameter check
+if isempty(varargin)
+    return;
+end
+
+if length(varargin) == 1 && iscell(varargin{1})
+    varargin = varargin{1};
+end
+
+%% Check all levels
+currentLevel = pStructure;
+for i = 1:length(varargin)
+    if isfield(currentLevel, varargin{i})
+        currentLevel = currentLevel.(varargin{i});
+    else
+        return;
+    end
+end
+
+boolean = true;
+
+end
+